#include <bits/stdc++.h>
using namespace std;

int main(){
  int n,a;
  cin >> n >> a;
  int x;
  int avg=0;
  for(int i=0;i<n;i++){
    cin >> x;
    avg+=x;
  }
  cout << ((double)avg/n==a?"YES":"NO") << endl;

  return 0;
}